The invention concerns a spacing piece for an essentially cylindrical tool on whose circumference blades with the shape of segments of arc are affixed with spacers between them by means of bolts extending in the axial direction through the spacers, the spacers consisting of steel sheet and displaying tangs, which determine the distance between neighboring blades, that are bent out of the plane, as well as a process for the production of such a spacer in which stampings are performed on a sheet metal blank corresponding to the desired height of the tangs and the tangs are bent out of the plane of the sheet metal blank preferably at an angle of 90.degree., and perforations are stamped out for the connecting bolts.
In spacing pieces according to the state of the art, especially spacing pieces according to Austrian patent [AT] 327 711 or AT 361 790, the primary objective is to improve the air circulation between the arc-segment-shaped tools arranged neighboring one another in the axial direction. The design according to AT 361 790 has the simultaneous objective of reducing the weight of the spacer, while the design according to AT 361 790 discloses essentially radial channels through which air can circulate. A disadvantage of this known design according to AT 361 790 is the fact that the perforation from which the tangs extending in the radial directions are bent out limit the free space for the arrangement of perforations for receiving the connecting bolts for the blades and that therefore with regard to the necessary stability of the spacer the tool cannot subsequently be adjusted to different blades with different hole distances for receiving connecting bolts. For different blades, besides a full distance that is optional within broad limits for receiving the mounting bolts, frequently a different distance must be maintained for neighboring blades, and in the case of the spacers known from AP 361 790, in such a case the entire manufacturing tool, especially the stamping tool as well as the bending tool must be modified in order to be able to produce spacers with different heights and therefore different distances between neighboring blades. For the production of such spacers, therefore, a significantly greater cost is sustained if different heights and different hole distances are to be achieved for mounting the blades. It has also been found that as a result of the increase in the air circulation a satisfactory cooling cannot be assured directly on the most strongly thermally stressed regions of the blades. The blades dipping into the material, e.g. a tire being prepared for retreading, are most strongly thermally loaded on their cutting edges, and the service life of such blades can then be effectively lengthened if the heat produced at this place can be carried off as close to the cutting edge as possible.